Sir Alex Ferguson says David Beckham had to leave Manchester United because the former England captain thought he was "bigger than the manager". In his latest autobiography, Ferguson said he fell out with Beckham after criticising his performance during an FA Cup defeat to Arsenal in 2003.

"The minute a Manchester United player thought he was bigger than the manager, he had to go," he wrote. "David thought he was bigger than Alex Ferguson. "That was the death knell for him." Beckham, who won six Premier League titles, two FA Cups and one Champions League crown during his United career, was eventually sold to Real Madrid for £25m in the summer of 2003.

He helped the Spanish giants win La Liga before moving to the United States, where he guided LA Galaxy to victory in the MLS Cup. Ferguson retired from management in May, ending one of the most successful managerial reigns in British history. During his 26 years in charge at Old Trafford, he won 38 trophies and managed some of the biggest names in football, like Beckham, Eric Cantona, Cristiano Ronaldo, Peter Schmeichel, Bryan Robson, Roy Keane, Jaap Stam and Ruud Van Nistelrooy.

Ferguson, whose 26-year reign as Manchester United boss ended in May, also writes in Alex Ferguson: My Autobiography that: Wayne Rooney lost his "old thrust" in his final season in charge because he was not fit enough Cristiano Ronaldo was the "most gifted player" he managed and calls him a "wizard" He told Ronaldo that he would rather "shoot" him than sell him to Real Madrid The reason he fell out with Rafa Benitez is because the Spaniard made his attacks personal Rio Ferdinand's eight-month ban for missing a drugs test in 2003 was too severe.

The hardest part of Roy Keane's body is his tongue and he has the most "savage tongue you can imagine" England will not win a World Cup until they can produce players as technically gifted as Brazil Ferguson also describes in detail his version of the dressing-room bust-up with Beckham that followed the FA Cup loss to Arsenal.

"He was around 12 feet from me," wrote Ferguson. "Between us on the floor lay a row of boots. "David swore. I moved towards him and, as I approached, I kicked a boot. It hit him right above the eye. "Of course, he rose to have a go at me and the players stopped him. 'Sit down,' I said. 'You've let your team down. You can argue as much as you like.'

"I called him in the next day to go through the video and he still would not accept his mistake. As he sat listening to me, he didn't say a word. Not a word. "'Do you understand what we're talking about, why we got on to you?' I asked. He didn't even answer me. "The next day the story was in the press. In public, an Alice band highlighted the damage inflicted by the boot. "It was in those days that I told the board David had to go."

Ferguson also allowed Ronaldo to leave Old Trafford, but only after Real Madrid had agreed to pay £80m for the winger. "Cristiano was the most gifted player I managed," wrote Ferguson. "He surpassed all the other great ones I coached at United - and I had many.

"The only ones who could be placed near him would be a couple of the home-produced players, Paul Scholes and Ryan Giggs, because they contributed so prodigiously to Manchester United for two decades."

Ferguson's trophy haul includes 13 league titles, two Champions League crowns, five FA Cups and four League Cups. He was replaced by fellow Scot David Moyes, who left Everton to take the Old Trafford job. Under Moyes, the defending Premier League champions have made their worst league start in 24 years and lie eighth in the table, eight points adrift of leaders Arsenal.